The present disclosure relates to methods, compositions, and systems for treating subterranean formations to reduce the formation of scales therein.
Oilfield fluids (e.g., oil, gas, and water) are generally complex mixtures of aliphatic hydrocarbons, aromatics, hetero-atomic molecules, anionic and cationic salts, acids, sands, silts, clays and a vast array of other components. The nature of these fluids combined with sometimes severe conditions of heat, pressure, and turbulence to which they are often subjected during retrieval, are contributory factors to scale formation in oil and/or gas production wells and surface equipment. Wherever water production occurs, the potential for some type of scale formation exists. “Scale,” as the term is used herein, may refer to any mineral or solid salt deposit that forms in a formation, for example, when the saturation of formation water to one or more minerals is affected by changing physical conditions (such as temperature, pressure, or composition), thus causing minerals and salts previously in solution to precipitate into solids. Scale deposits may comprise a variety of materials, including but not limited to calcium carbonate, magnesium carbonate, calcium sulfate, magnesium sulfate, barium sulfate, strontium sulfate, iron sulfides, and the like. Scale deposits can form on any surface in a down hole operation, including subterranean formations, production tubing, gravel packing screens, and other well bore equipment. Scale can develop almost immediately, or build up over several months before becoming noticeable. The effect scale has on productivity depends on the type, location, and the mass deposited. Scale formation can become so severe as to restrict or even completely choke production. The formation of scale can decrease permeability of the subterranean formation, reduce well productivity and shorten the lifetime of production equipment. In order to clean scale from wells and equipment it is generally necessary to stop production, which is both time-consuming and costly.
The formation of scale is often controlled by the use of chemical scale inhibitors that reduce or prevent the precipitation and/or deposit of these scales in the formation. Several methods are known in the art for introducing scale inhibitors into production wells. For example, a solid form of a scale inhibitor may be placed into the formation; however, this method may be limited due to the fact that there are relatively few effective solid scale inhibitors and each has functional or design limitations. Another known method of placing scale inhibitor is a “squeeze” application in which a scale inhibitor is introduced into a formation and adsorbed or precipitates onto the reservoir rock surfaces and helps prevent or diminish scale deposition. However, in conventional applications of these methods, it may be difficult or impossible to confirm whether the scale inhibitor has been adsorbed onto the rock surface with sufficient mechanical strength to avoid displacement by fluids flowing through the formation, and in an adequate amount to provide effective scale inhibition. In some cases, it may be difficult and/or require long periods of shut-in time to allow the scale inhibitor to adequately adsorb onto rock surfaces downhole.
While embodiments of this disclosure have been depicted, such embodiments do not imply a limitation on the disclosure, and no such limitation should be inferred. The subject matter disclosed is capable of considerable modification, alteration, and equivalents in form and function, as will occur to those skilled in the pertinent art and having the benefit of this disclosure. The depicted and described embodiments of this disclosure are examples only, and not exhaustive of the scope of the disclosure.